1. Field of the Invention
This invention relates to agricultural equipment and in particular to a combine for harvesting and threshing grain having a conveyor for transporting both clean grain and grain returns to a grain bin and threshing rotor, respectively. The grain bin is pivotally mounted adjacent to an unloader to facilitate the flow of clean grain from the grain bin so that it may be discharged from the combine.
2. Description of the Prior Art
Combines and agricultural equipment employing a grain bin for temporary storage of grain have used grain bins which are immovably mounted to the combine. In order to remove grain from the grain bin, the floor of the grain bin is sloped toward an opening which is in communication with a grain auger for discharging the grain from the combine or agricultural equipment. The sloped floor of the grain bin causes grain to flow through the opening but reduces the volume of the grain bin thereby reducing the amount of grain that can be stored.
When the grain bin is full, the grain is discharged by means of an auger which receives the grain as the grain flows through the opening. Because grain augers require very high forces and energy to elevate grain, the use of an auger is very inefficient. Augers tend to crack and damage the grain and are very hard to clean.
In most combines, clean grain is separated from tailings and chaff by the use of sieves. A blower blows air across the sieves to discharge the lighter chaff as clean grain falls through the sieves and is conveyed up to the grain bin. Tailings, which are too heavy to be blown away from the combine but too large to fall through the sieves, will sometimes contain grain. To prevent the loss of this grain, the tailings or grain returns must be collected and rethreshed.
U.S. Pat. No 4,489,733 describes an axial flow combine with elevating rings which extend circumferentially around the body of the combine. The elevating rings have separate compartments for both grain returns and clean grain. The elevating rings rotate causing grain returns and clean grain to be delivered to a threshing rotor and a grain bin, respectively. Because of the circular shape of the elevating rings, however, the elevating rings require a great deal of space.
For the above reasons, there exists a need for a grain bin having a large capacity which allows grain to flow easily from the grain bin for discharge, and for a combine that has a means for returning grain to the grain bin and tailings to a threshing rotor for rethreshing in a simple but effective way without requiring a large amount of space.